Method for forming end bearing concrete piles



Jan 28, 1969 w. B. GOODMAN METHOD FOR FORMING END BEARING CONCRETE PILESFiled Aug. 28, 1967 FIG. 2

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w.B.eooDMAN en? 73M Hls ATT RNEY United States Patent O .4 ClaimsABSTRACT OF THE DISCLOSURE An elongated borehole forming tubular member,having a cheek valve intermediate its ends, is sonically driven into anearth formation to a predetermined depth to form a borehole, thenwithdrawn a short distance from the bottom of the hole as a slurry ofconcrete or cement is pumped through the tubular member and through thecheck valve into the hole. The tubular member is again sonically drivendownward with the valve closed forcing the cement outward into anenlarged bulbular shape in the formation. The tubular member is thenwithdrawn from the hole as it is being sonically vibrated and cement ispumped through the tubular member into the hole to form the body of thepile.

BACKGROUND OF THE INVENTION Field of the invention y In the constructionof buildings, bridges, piers, drilling platforms and other similarstructures, it is essential that a solid, stable foundation beestablished on which to rest the structures. Such foundations aregenerally established by sinking a number of piles into the earth onwhich t rest the structure. The load capacity of these piles dependsupon such factors as soil conditions and size, shape and length of thepilings. The resistance of a pile to displacement in an earth formationis provided by friction along the length of the pile and on tipresistance or resistance by the soil to displacement by the end or tipof the pile. In some soils very little shaft resistance is encountered,in which case, tip `or end resistance must carry the entire load.

The type of soil into which the pile is driven has an important bearingupon its load carrying capacity. For example, piles which are sunk intoclay type soils carry most of the applied load by soil friction 'alongtheir shaft length. Very little resistance is supplied by the tip. Onthe other hand, piles which are placed into a sandy type of formationcarry most of the applied load by tip resistance when the load actsdownward, and very little of the load is carried by soil friction alongthe shaft.

It has been found that an ideal shape for an end or tip bearing pilewould be one having a large or bulbous base or foot, and a normal orregular sized sh-aft. Such a shape for such piles would offer' greatsavings in materials in that the length and diameter of the shaft ofsuch a pile would be much less than for a pile of constant diameterhaving the same load carrying capacity'.

The present invention relates to the construction in place of concretepiles and pertains more particularly t0 a method for the forming inplace of end bearing piles having a large bulbular base or foot andtherefore a high load capacity.

Description of prior art Various methods are known for constructingbulbular or large based piles. One method is known as the Franki method.In accordance with this method a specially constructed rig is moved tothe construction site. A casing or heavy gauge, high-tensile alloy steelis raised in place. A portion of very dry concrete is then placed in thebottom of the casing to form a driving plug. Next, a heavy, solid rarnweighing from two to four tons is lowered into the casing and raised infront to drive the plug into the ground which pulls or carries thecasing with it by means of friction between it and the casing. At thedesired level the casing is then anchored to the rig and the plug drivenout the bottom of the casing. More concrete is then dumped into thecasing and rammed out the bottom of the casing to form the bulb. Thecasing is then raised small increments as more concrete is dumped intothe casing and rammed out the bottom to form the rest of the pile.

Among the disadvantages of the prior known methods of constructing suchbulbular base piles is that the steps are long and slow. Such methods,being time consuming, are therefore expensive.

Furthermore, the apparatus used in such prior known methods is heavy,complicated and cumbersome. This also adds to the cost of constructingsuch piles.

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to overcome the above and other disadvantages of such priormethods and apparatus by providing a method and apparatus that is rapidand efficient for the construction in place of high load capacity piles.

It is a further object of the present invention to provide a method thatis simple, easy to use and rapid in the formation in place of high loadcapacity piles.

Still another object of the present invention is to provide a method offorming bulbular base piles that utilizes a sonic vibratory driving headIas power means for forming the bulbular base.

A further object of the present invention is to provide a method offorming bulbular base piles that takes advantage of the power andeiciency of a sonic driving head to form the borehole and the bulbularbase for the pile.

Still -a further object of the present invention is to provide a methodof forming a bulbular base pile that takes maximum advantage of thevarious load carrying capacities of the various strata in an earthformation.

In accordance with the invention, an elongated borehole forming tubularmember having a check valve in the bore intermediate the ends thereof isprovided with a driving tip and sonically driven to a predetermineddepth. The tubular member is then wtihdrrawn a predetermined amount as aslurry of solidiable material such as cement is pumped through thetubular member and through the valve filling the borehole and the boreof the tubular member with a column of solidiable material. The tubularmember is then sonically driven downward with the valve closed, forcingthe column of material downward and the lower portion thereof outwardinto the formation forming an enlarged bulbous base. The tubular memberis sonically vibrated as it is withdrawn and as more of the material issimultaneously injected into the borehole to form the body of the pile.

BRIEF DESCRIPTION OF THE DRAWING The above and other objects andadvantages will become apparent from the following description used toillustrate a preferred embodiment of the invention when read inconnection with the accompanying drawings in which:

FIGURE 1 is a diagrammatic View, partially in section, of apparatus usedin carrying out the present invention driven to the desired depth in anearth formation.

FIGURE 2 is a diagrammatic View, partially in section, through theborehole showing the tool member partially withdrawn from the bottom ofthe borehole.

FIGURE 3 is a diagrammatic view, partially in section, through theborehole and partially in section through the tool, showing the base ofthe pile after it has been formed.

FIGURE 4 is a diagrammatic view, partially in section through theborehole showing the base of the pile and a portion of the shaft ascompleted and the tool being withdrawn.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, apreferred embodiment of an apparatus for carrying out the presentinvention is illustrated. In FIGURES 1-4 a :bore-forming tool 11 isconnected in any suitable 'manner such as by a clamp or flange 12 to asonic driving head 13, which is supported by means of a cable orilexible member 14 from any suitable derrick or crane-like structure,not shown. The bore-forming tool 11 generally comprises an elongatedelastic tubular member 14 having a check valve 16, intermediate the endsthereof at a predetermined point above the lower end to close off thebore thereof. A cap or driving plug 17 is generally provided to closethe lower or driven end of the tubular member. A conduit 18 locatedabove the check valve 16 leads from a suitable source, not shown, ofsolidiiiable material, such as cement or concrete, which is to be pumpedthrough the bore of the tool member and into the formation.

The sonic method of driving piles and the underlying theory is disclosedin U.S. Patent No. 2,975,846, issued to A. G. Bodine. Reference is madeto the aforesaid patent for suitable sonic generators as well as adetailed explanation of the sonic pile driving method. Briey, thismethod comprises acoustically coupling a sonic generator to the upperend of a pile and operating the sonic generator so as to set uplongitudinal standing waves in the pile with the lower end of the pilein tight engagement with the earth. The pile then :buries itself bysonic standing wave action.

OPERATION In operation, the pile forming tool 11 is hoisted into placewith cap 17 in place on the lower end thereof. The sonic driving head 13is started up and the tool driven to a predetermined depth as shown inFIGURE l. The tool is then withdrawn a distance from the bottom of thebore hole as shown in FIGURE 2 and a slurry of solidifiable fiuidmaterial such as cement or concrete is pumped through the bore of thetool into the bottom of the borehole. The sonic driver 13 is thenstarted up and the tool 11 sonically driven downward. The increasedpressure on the column of material 19 from driving the tool downwardcloses check valve 16, trapping the column of material and forcing aportion of it downward and the exposed walls of the borehole outwardinto the formation, thus forming an enlarged base or footing 20 for thepile as seen in FIGURE 3. This process of trapping and driving a columnof the material downward is repeated if necessary until a sufficientvolume of the material is displaced into the formation to form asuitable sized base 20 for the pile. After a suitable base has beenformed, the tool is withdrawn from the formation while being sonicallyvibrated and a slurry of the solidifiable material is continuously fedinto the bore to form the column of the pile as shown in FIGURE 4.

It can also be appreciated that the lower or driven end of tube 15 mayalso be closed off without the use of plug 17. This may be accomplishedby placing the open end of the tubular member 15 against the earthformation and then lling the tube or bore thereof with the solidifiablematerial. The column of material thus trapped will act as a plug toprevent the entrance of earth material into the bore of the tubularmember.

It may also be appreciated that the present invention is not limited tothe yforming of piles vertically in an earth formation, but may be usedfor forming piles that may be set at various angles to the vertical. Forexample, horizon tal pilings may be formed in place by the method of thepresent invention.

I claim as my invention:

1. A method of forming a bulbular based pile comprising the steps of:

providing an elongated pile forming member with an axial bore thereinand valve means yfor closing said bore at a predetermined point abovethe lower end thereof;

temporarily closing said lower end of said member;

sonically forcing said one end of said elongated 'member into an earthformation to a predetermined depth, to thereby form a material-receivingborehole in said formation;

withdrawing said elongated member a predetermined distance from thebottom of said material-receiving borehole, to thereby expose a portionof the wall of said borehole;

substantially filling said material-receiving horehole and said bore ofsaid elongated member below said valve means with a slurry of solidiablematerial, to thereby form a column of said material;

closing said valve means to confine said material in said bore', and

sonically forcing at least a portion of said column of materialdownward, and at least a portion of the exposed walls of said earthborehole outward to form an area of said material of enlarged diameter.

2. The method of claim 1 further including the steps of:

withdrawing said elongated member while sonically vibrating said member;and

feeding additional solidiable material through the valve means and boreof said member and into said material-receiving borehole.

3. The method of claim 1 wherein the step of closing said one end ofsaid member includes:

placing a removable cap over said one end.

4. A 'method of forming a bulbular based pile comprising the steps of:

providing an elongated pile forming member with an axial bore thereinand valve means for closing said bore at a predetermined point above thelower end thereof;

temporarily closing said lower end of said member by placing said end ofsaid member into contact with said earth formation;

filling said bore of said member at least up to said valve means with aslurry of solidifable material under pressure;

sonically forcing said one end of said elongated member into an earthformation to a predetermined depth, to thereby form a material-receivingborehole in said formation;

withdrawing said elongated member a predetermined distance from thebottom of said material-receiving borehole, to thereby expose a portionof the wall of said borehole;

6 substantially filling said material-receiving borehole and ReferencesCited said bore of said elongated lmember below said valve UNITED STATESPATENTS means with a slurry of solidiable material, to thereby form acolumn of said material; 1g; vegton "EIMS-3235? closing said valve meansto confine said material in e, er

said bore; and 5 I 3,187,513 6/1965 Gund 61 53.5

sonically [forcing at least a portion of said column of JACOB SHAPIROPrimary Examiner material downward, and at least a portion of theexposed walls of said earth borehole outward to U S` C1, X,R, form anarea of said material of enlarged diameter. 10 6l-53.66

